Wireless communications involving the transmission and reception of data packets and other types of information via wireless, cellular and/or mobile techniques provide the backbone of our information society with widespread business and non-business applications. Hereinafter, such techniques will be simply referred to as “mobile communications” merely for the sake of brevity.
In a typical mobile communications system, a plurality of mobile stations (e.g., cellular/mobile phones, laptop computers, personal digital assistants (PDAs), etc.) are served by a network of base stations, which allow the mobile stations to communicate with other components in the communications system.
Mobile communications systems can include cellular, personal communication services (PCS), Global System for Mobile communications (GSM), IMT-2000 and the like. Each type of system employs an air-interface standard, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), etc., which are multiple access methods. These types of systems are characterized by the bandwidths used during signal transmissions.
Mobile communications systems and standards can be classified as 1st generation analog type systems, 2nd generation digital type systems (2G), and 3rd generation upgraded digital type systems (3G). Two popular standards of the digital type 2G mobile communications systems include GSM systems that use TDMA as its air interface technology, and CDMA systems that use CDMA technology.
The 3G mobile communications standards are known as IMT-2000 or Universal Mobile Telecommunications System (UMTS), which reflect various enhancements and improvements of 2G mobile communications systems that are specified and standardized by two standardization bodies, i.e., the Third Generation Partnership Project (3GPP) and the Third Generation Partnership Project Two (3GPP2). The 3G mobile communications standards are not yet fully deployed as commercial systems, but are expected to be commercialized in the near future.
The service area of typical mobile communications system is divided into many cells. The system is called as “cellular system”. Each cell of a cellular system has its own coverage area and has at least one base station connected to the overall communications network. However, the base station cannot cover all portions of its service area with the same performance. A mobile station and a base station may have difficulties in establishing proper signal links therebetween due to many different reasons. For example, signal interference or obstruction may result from terrain characteristics or various obstacles such as buildings. The mobility characteristics of the mobile station may cause difficulties in establishing and maintaining communication links. To prevent communication disruptions, one or more repeaters may be placed within appropriate regions of a cell so that signal transmissions between mobile stations and base stations are improved.
Typically, a repeater (or a repeater system) may be needed to support the base station to communicate with a mobile station in certain regions within the service area. A repeater may be used in a mobile communications system for relaying and/or boosting signals between a mobile station and a base station. Thus, within a cell, there can be a base station with additional repeaters that amplify and transfer the base station signals to the mobile stations.
Here, it should be noted that there are several types of repeaters. Depending upon the type of link being established with the base station, repeaters can be a fiber optic repeater or a radio frequency (RF) repeater. Typically, fiber optic repeaters and RF repeaters can have different types of signal influence problems. The present disclosure will focus on RF signal transmission technology pertaining to signal transmission and reception via an air interface.
An essential part of wireless or mobile communications includes antenna systems employing different types of antennas. Mobile communications involve the transmission and reception of radio frequency (RF) waves having high frequencies. A base station typically includes a transmitter antenna, a receiver antenna, a digital processing part and an amplifier or analog processing part. A transmitter antenna converts electrical signals into airborne radio frequency (RF) waves, while a receiver antenna converts airborne RF waves into electrical signals. A repeater can have a similar structure as a base station, but do not include a digital processing part. Signals are merely amplified by an amplifier or analog processing part. Typically, a repeater can have a donor antenna and a distributor (or coverage) antenna, which can each transmit and receive signals to and from the base station.
A repeater can consist of various components required for transmitting and receiving signals between a mobile station and a base station. An important part of a repeater is an antenna assembly A as shown in FIG. 1A.
For example, a conventional repeater antenna assembly A includes a radiator/receiver array 1 having a plurality of radiator elements or modules that can receive signals of different polarizations. Typically, the radiator/receiver array 1 is mounted in front of a rectangular reflector plate 3 so that signal transmission and reception is improved. The front portion of the reflector plate 3 having the radiator/receiver array 1 mounted thereto faces towards the direction of the desired signal transmission and reception. A cover (not shown) is typically placed over the front portion of the reflector plate 3 to protect the radiator/receiver array 1.
Conventional repeater antenna assemblies for mobile communications have rectangular reflector plates 3 that are flat and made of a conductive material such as metal. The flat rectangular reflector plate 3 is positioned so that its longer side is approximately vertical to the horizon as shown in FIG. 1A. As such, the reflector plate has a length (vertical height) and a width (breadth). The length is of an appropriate dimension to allow signal transmission and reception in the vertical direction, while the width is of an appropriate dimension to allow signal transmission and reception in the horizontal direction.
Also, in a conventional repeater antenna assembly A, the flat rectangular reflector plate 3 having the radiator/receiver array 1 is attached to a support pole 5 via a fixing means 7, as shown in FIG. 1A. Typically, the support pole 5 is made of steel or other metal that provides sufficient strength to hold up the reflector plate 3 and radiator/receiver array 1, while being resistant to wind loading. In general, the fixing means 7 is also made of metal to provide secure attachment of the reflector plate 3 to the support pole 5.
Additionally, the conventional repeater antenna assembly A includes a feed network (feeder) 9 electrically connected with the radiator/receiver array 1 via cables and wires for providing electrical signals thereto.
Typically, the cables and wires of the feed network 9 are connected with the radiator/receiver array 1 from behind the reflector plate 3, as shown in FIG. 1A.
For conventional mobile communications systems, a repeater system can have at least one repeater functioning as a receiver antenna (e.g., a donor antenna) and at least another repeater functioning as a transmitter antenna (e.g., a coverage antenna). The donor antenna sends and receives signals to and from the base station, while the coverage antenna sends and receives signals to and from the mobile station.